impregnated on small strips of paper that are placed on the tongue. Largescale research of the population has shown that some people are highly sensitive to the bitter taste (the so-called “supertasters”, who are also more sensitive to sweet and spicy sensations) and they therefore have a low taste threshold, while others have low sensitivity (the “non-tasters”) and a high taste threshold. There is often an intermediate category in the classification, the “medium-taster”. Moreover, sensitivity to bitterness varies widely in the world: non-tasters represent nearly 3% of the population of West Africa, over 40% of Indians and 30% of Europeans. The great variability in receptors for bitterness explains, for example, that a non-taster will like bitter coffee without sugar, certain kinds of beer, vegetables or bitter chocolate with 70% cocoa. The Sense of Taste and Human Evolution
The sense of taste has been transformed, in the course of the evolution of mammals, into a system capable of determining whether potential foodstuffs are useful or harmful. The preference for sweet food is related to the search for food with a high calorie count; the umami taste, for food rich in proteins; and the liking for salt to the need to ingest a certain amount of mineral salts. In general, all human populations feel an aversion towards sour and very bitter food. High acidity levels may indicate the presence of contaminated food. This possibility, obviously more frequent in the past than now, has remained as a widespread attitude in order to assess whether or not food has been properly preserved. However, these innate behaviour patterns are influenced by a population’s eating habits and culture, as, for example the salty, and especially the sour, tastes are obvious from the habit of eating food preserved with salt or vinegar. It is reasonable to suppose that an aversion to bitterness is due to the fact that many of the compounds harmful to health are found in vegetables and taste bitter, and so our body has developed a preventive defence system against these risks. The alkaloids, for example, that are contained in around 20% of plant species and which taste bitter, are noted for their toxicity (strychnine or atropine), for their stimulating effects on the nervous system (caffeine and theobromine), or for being drugs (cocaine and mescaline). It is therefore easy to understand how plants with a bitter taste have always been regarded with suspicion and caution in the history of human evolution.
Xavier Estivill - Raquel Rabionet - Mònica Gratacòs
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